Editing Sailing (section)

===Course under sail===
[[File:Atmospheric circulation.svg|thumb|[[Atmospheric circulation]], showing wind direction at various latitudes]]
[[File:Occluded cyclone.svg|thumb|Wind circulation around an [[Weather front#Occluded front|occluded front]] in the Northern Hemisphere]]
Wind and currents are important factors to plan on for both offshore and inshore sailing. Predicting the availability, strength and direction of the wind is key to using its power along the desired course. Ocean currents, tides and river currents may deflect a sailing vessel from its desired course.<ref name = Offshore>
{{cite book
 | last1 = Howard
 | first1 = Jim
 | last2 = Doane
 | first2 =  Charles J.
 | title = Handbook of Offshore Cruising: The Dream and Reality of Modern Ocean Cruising
 | date = 2000
 | url = https://books.google.com/books?id=NB4uFQuUlnEC&pg=PA214
 | page = 214
 | publisher = Sheridan House
 | isbn = 9781574090932 }}</ref>

If the desired course is within the no-go zone, then the sailing craft must follow a zig-zag route into the wind to reach its waypoint or destination. Downwind, certain high-performance sailing craft can reach the destination more quickly by following a zig-zag route on a series of broad reaches.

Negotiating obstructions or a channel may also require a change of direction with respect to the wind, necessitating changing of tack with the wind on the opposite side of the craft, from before.

Changing tack is called ''tacking'' when the wind crosses over the bow of the craft as it turns and ''jibing'' (or ''gybing'') if the wind passes over the stern.

====Upwind====
A sailing craft can sail on a course anywhere outside of its no-go zone.<ref name=Cunliffe>
{{cite book
 | last = Cunliffe
 | first = Tom
 | title = The Complete Day Skipper: Skippering with Confidence Right From the Start
 | publisher = Bloomsbury Publishing
 | edition = 5
 | date = 2016
 | page=46
 | url = https://books.google.com/books?id=9b-gCwAAQBAJ&pg=PA46
 | isbn = 978-1-4729-2418-6 }}</ref> If the next waypoint or destination is within the arc defined by the no-go zone from the craft's current position, then it must perform a series of [[Tacking (sailing)|tacking maneuvers]] to get there on a zigzag route, called ''beating to windward''.<ref name=Cruising>
{{cite journal|last=Cunliffe|first=Tom|date=January 1988|title=The shortest route to windward|url=https://books.google.com/books?id=InheK-WGcAcC&pg=PA63|journal=Cruising World|volume=14|issue=1|pages=58–64|issn=0098-3519}}</ref> The progress along that route is called the ''course made good''; the speed between the starting and ending points of the route is called the ''speed made good'' and is calculated by the distance between the two points, divided by the travel time.<ref name=Jobson2>
{{cite book
 | last = Jobson
 | first = Gary
 | title = Sailing Fundamentals
 | publisher = Simon and Schuster
 | edition = Revised
 | date = 2008
 | pages = 224
 | url = https://books.google.com/books?id=mKTrrP3wA-cC
 | isbn = 978-1-4391-3678-2 }}</ref> The limiting line to the waypoint that allows the sailing vessel to leave it to leeward is called the ''layline''.<ref name=Positioning>
{{cite book
 | last1 = Walker
 | first1 = Stuart H.
 | last2 = Price
 | first2 = Thomas C.
 | title = Positioning: The Logic of Sailboat Racing
 | publisher = W. W. Norton & Company
 | date = 1991
 | page = 192
 | url = https://books.google.com/books?id=5RWPv7tBnDsC&pg=PA192
 | isbn = 978-0-393-03339-7 }}</ref> Whereas some [[Bermuda rig|Bermuda-rigged]] sailing yachts can sail as close as 30° to the wind,<ref name=Jobson2/> most 20th-Century square riggers are limited to 60° off the wind.<ref name=Findlay>
{{cite book|last=Findlay|first=Gordon D.|url=https://books.google.com/books?id=OzFWjOMvGs4C&pg=PA138|title=My Hand on the Tiller|date=2005|publisher=AuthorHouse|isbn=9781456793500|page=138}}</ref> [[Fore-and-aft rig]]s are designed to operate with the wind on either side, whereas [[square rig]]s and [[kite]]s are designed to have the wind come from one side of the sail only.

Because the lateral wind forces are highest when sailing close-hauled, the resisting water forces around the vessel's keel, centerboard, rudder and other foils must also be highest in order to limit sideways motion or [[leeway]]. Ice boats and land yachts minimize lateral motion with resistance from their blades or wheels.<ref name=Fabio>{{cite book
 | last = Fossati
 | first = Fabio
 | title = Aero-hydrodynamics and the Performance of Sailing Yachts: The Science Behind Sailing Yachts and Their Design
 | publisher = Adlard Coles Nautical
 | date = 1 November 2009
| pages = 352
 | isbn = 978-1408113387 }}</ref>

=====Changing tack by tacking=====
{{Further|Tacking (sailing)#For various sailing craft}}
[[File:Canada and Vencedor – 1896.jpg|thumb|Two sailing yachts on opposite tacks]]
''Tacking'' or ''coming about'' is a maneuver by which a sailing craft turns its [[bow (ship)|bow]] into and through the wind (referred to as "the eye of the wind"<ref>{{Cite book |last=Ell |first=Sarah |url=https://books.google.com/books?id=DgxobVjcJSgC&dq=sailingl+%22eye+of+the+wind%22&pg=PA49 |title=Dinghy Sailing |date=2002 |publisher=Stackpole Books |isbn=978-0-8117-2474-6 |pages=49 |language=en}}</ref>) so that the apparent wind changes from one side to the other, allowing progress on the opposite tack.<ref name=Keegan>{{cite book |last=Keegan |first=John |author-link=John Keegan |title=The Price of Admiralty |publisher=Viking |date=1989 |location=New York |page=[https://archive.org/details/priceofadmiralty00keeg/page/281 281] |isbn=978-0-670-81416-9 |url=https://archive.org/details/priceofadmiralty00keeg/page/281 }}</ref> The type of sailing rig dictates the procedures and constraints on achieving a tacking maneuver. Fore-and-aft rigs allow their sails to hang limp as they tack; square rigs must present the full frontal area of the sail to the wind, when changing from side to side; and [[windsurfer]]s have flexibly pivoting and fully rotating masts that get flipped from side to side.
<gallery mode="packed" heights="250px">
File:Wende (Segeln).png|Tacking from the port tack (bottom) to the starboard (top) tack
File:Tacking Intervals.svg|Beating to windward on short (P1), medium (P2), and long (P3) tacks
</gallery>

====Downwind====
[[File:18foot skiff Kiel2008.jpg|thumb|[[18ft Skiff]], flying a sprit-mounted asymmetrical spinnaker on a broad reach]]
A sailing craft can travel directly downwind only at a speed that is less than the wind speed. However,  some sailing craft such as [[iceboat]]s, [[land yacht|sand yachts]], and some [[High-performance sailing|high-performance sailboats]] can achieve a higher downwind [[velocity made good]] by traveling on a series of broad reaches, punctuated by jibes in between. It was explored by sailing vessels starting in 1975 and now extends to high-performance skiffs, catamarans and foiling sailboats.<ref name=Bethwaite>{{cite book|last =Bethwaite|first=Frank|title=High Performance Sailing|publisher=[[Adlard Coles]] Nautical|year=2007|isbn = 978-0-7136-6704-2|url=https://books.google.com/books?id=WTRLAAAAQBAJ}}</ref>

Navigating a channel or a downwind course among obstructions may necessitate changes in direction that require a change of tack, accomplished with a jibe.

=====Changing tack by jibing=====
{{Further|Jibe#For various sailing craft}}
''Jibing'' or ''gybing'' is a sailing maneuver by which a sailing craft turns its [[stern]] past the eye of the wind so that the apparent wind changes from one side to the other, allowing progress on the opposite tack. This maneuver can be done on smaller boats by pulling the tiller towards yourself (the opposite side of the sail).<ref name=Keegan/> As with tacking, the type of sailing rig dictates the procedures and constraints for jibing. Fore-and-aft sails with booms, gaffs or sprits are unstable when the free end points into the eye of the wind and must be controlled to avoid a violent change to the other side; square rigs as they present the full area of the sail to the wind from the rear experience little change of operation from one tack to the other; and [[windsurfer]]s again have flexibly pivoting and fully rotating masts that get flipped from side to side.